Thermal analysis of Malaysian double storey housing - low/medium cost unit

Almost half of the total energy used today is consumed in buildings. In the tropical climate, air-conditioning a housing unit takes much of the energy bill. Malaysia is no exception. Malaysian double storey terrace housing is popular among developers and buyers. Surveys have shown that housing occupants are much dissatisfied with the thermal comfort and artificial cooling is often sought. The objective of this study is to assess the thermal comfort of the low and medium-cost double storey housing in the area surrounding Universiti Teknologi Malaysia. A simulation program using the Weighting Factor Method calculates the heat transfer interaction, temperature distribution, and PMV level in three types of housing units in relation to the size. Fanger's PMV model based on ISO Standard 7730 is used here because it accounts for all parameters that affect the thermal sensation of a human within its equation. Results showed that both the low and medium-cost housing units studied are out of the comfortable range described by ASHRAE Standard 55 with the units all complied with the local bylaws. In view of the uncertainties in energy supply, future housing units should consider natural ventilation as part of the passive energy management

Effect of water on polypropylene/barium titanate nanocomposites

In high voltage systems, it is important to have good insulation systems in order to transfer power over a long distance. The use of polymer nanocomposites could make differences in insulation system. However, the presence of water in nanocomposites could negatively affect the performance of nanocomposites as it is found that nanocomposites can absorb more water than unfilled polymers. This study investigated the AC breakdown strength of polypropylene (PP) as polymers blends with 1 wt%, 2 wt% and 5 wt% of barium titanate (BaTiO3) nanofiller and analyzed the effect of water absorption on breakdown strength of polypropylene added with different amount of barium titanate nanofiller. All the samples of nanocomposites were then subjected to water absorption process for certain periods which are 0 days, 10 days, and 20 days to evaluate how much water can be absorbed by the samples and its effect on breakdown strength of nanocomposites. While AC breakdown test was conducted according to standard of American Society for Testing ance Material (ASTM) D149 to correlate the effect of water absorption with the breakdown strength of nanocomposites containing barium titanate

Computation of current-resistance photovoltaic model using reverse triangular number for photovoltaic emulator application

PV emulator (PVE) is a power supply that produces similar current‑voltage (I‑V) characteristic as the PV module. It simplifies the testing of the PV system during the development phase. Since the output voltage and current of the PVE change based on various factors (load, irradiance and temperature), the computation of the operating point for the PVE is crucial. The resistance feedback control strategy is a robust and fast approach to find the operating point for the PVE. Nonetheless, it uses an uncommon current‑resistance PV model, which cannot be computed using the conventional approach. This work introduces the reverse triangular number to compute the PV model and obtained the operating point of the PVE. The reverse triangular number is based on the variable step sizes that allow fast computation of the PV model. The operating point is then used by the PI controller and the buck converter to produce the output voltage and current similar to the PV module. The results show that the reverse triangular number is able to compute the PV model accurately. In addition, the proposed PVE not only works well with resistive load but adapts accurately under the integration with maximum power point tracking converter

Polypropylene‐based nanocomposites for HVDC cable insulation

Cross-linked polyethylene (XLPE) is commonly used as an insulation material in power cables. Due to the recent advancements in the field of high voltage power transmission and distribution, there is a need for novel cable insulation materials that have high performance, recyclability and high working temperature as alternatives for the conventional XPLE-based insulation materials. Polypropylene (PP) shows excellent properties and has drawn considerable attention as a potential high voltage direct current (HVDC) insulation material. Therefore, the development of PP-based HVDC cable insulation with improved electrical, thermal and mechanical properties is important in discovering a potentially recyclable cable insulation material. Due to the remarkable development in the field of nanodielectrics, nanotechnology can be a promising solution for enhancing the overall dielectric properties of PP-based insulation materials. This review presents the important aspects of PP-based nanocomposites for HVDC cable insulation with a special focus on understanding the effects of various parameters of nanofillers on the dielectric properties of PP-based HVDC cable insulation. Based on the gathered information, future perspectives for improving the dielectric properties of PP-based nanocomposites for HVDC cable are provided

A review of the smart grid communication technologies in contactless charging with vehicle to grid integration technology

Power needs to be transferred from the source to the load (electric vehicle). Transmitting electricity through the air gap for charging using electromagnetic waves as one of the smart grid technologies called Wireless Power Transfer (WPT), or Inductive Power Transfer. This paper presents the fulfilment of future gird that addresses the issues of Greenhouse Gas emission, and transportation and industries emissions known as the smart grid with a complex system. The complexity of the smart grid communication system is the motivation to be an open area of research issue. The main contribution of this paper is to close the gap between this research and other researches by delivering a comprehensive review and update the recent state-of-the-art of smart grid communication technologies with the integration of vehicle-to-grid (V2G) technology using the contactless charging method. Smart grid communication technologies with their pros and cons, topologies of wireless communication, challenges of the V2G, WPT challenges, and standards are discussed. Therefore, this study is expected to be a significant guide to engineers and researchers studying in the field of smart grid communication technologies and contactless charging for electric vehicles

Investigation of high voltage polymeric insulators performance under wet pollution

In this paper, a unique approach based on electrical characteristics observed from measurements of contaminated polymeric insulators was established to calculate the electric field distribution over their surfaces. A case study using two different 33 kV polymeric insulator geometric profiles was performed to highlight the benefits of the proposed modeling approach. The conductance of the pollution layer was tested to establish a nonlinear field-dependent conductivity for pollution modeling. The leakage current (LC) of the polluted insulator was measured in a laboratory under clean and wet conditions. Then, using the finite element method (FEM), the electric field and current density distributions along the insulator were computed. The results showed that the insulators experienced an increase in the electric field (EF) magnitude ranging from 0.3 kV/cm to 3.6 kV/cm for the insulator with similar sheds (type I) and 2.2–4.5 kV/cm for the insulator with alternating sheds (big and small, type II) under the high rain condition with a flow rate of 9 L/h. Meanwhile, the highest electric field under fog was 1.74 kV/cm for the insulator with similar sheds and 2.32 kV/cm for an insulator with alternating sheds. Due to the larger diameter on the big shed and the longer leakage distance on the insulator with alternating sheds, the EF on the insulator with alternating sheds is higher than the EF on the insulator with similar sheds. The proposed modeling and simulation provided a detailed field condition estimation around the insulators. This is critical for forecasting the emergence of dry bands and the commencement of flashover on the surfaces of the insulators

Pollution flashover characteristics of coated insulators under different profiles of coating damage

Based on experiments and numerical analysis techniques, this paper aims to investigate the influence of the four different coating damage profiles on the performance of coated 33 kV porcelain insulator strings under polluted and clean surface conditions. The performance of the insulators coated with room temperature vulcanizing (RTV) under partial coating damage and undamaged coating was evaluated. The influence of humidity on pollution flashover was taken into consideration. The ring-shaped, fan-shaped, and random-shaped coating was applied following coating damage. The results showed that the flashover characteristic of the RTV-coated insulators had a significant difference as compared to the normal insulators. Electrical characteristics such as the flashover voltage, critical current, and surface resistance were significantly affected by coating damage distribution and humidity level on the insulators’ surface. The electric field and potential difference were analyzed as well using the finite element method (FEM). The initiation of the arc was observed to appear at the area of insulators where the electric field was the highest. It was also observed that different coating distributions of pollution and humidity levels resulted in a change in the surface pollution layer resistance and an uneven distribution of the electric field. This indicates that the coated insulators’ parameters are directly related to the coating damage distribution on the insulator surface, particularly in the presence of humidity

Polymer nanocomposites in high voltage electrical insulation perspective: a review

Polymer nanocomposites have attracted wide interests in various industries. This new class of material is capable of providing significant improvements in combined electrical, thermal and mechanical properties. Although the potential use of polymer nanocomposites in electrical insulating industry has only recently begun to be explored, a great number of researches have been conducted with regards to high voltage electrical insulation performance. However, it is found that the fundamental physics and chemistry concerning the property enhancement due to the incorporation of nanocomposites is still poorly understood, and there is still room for improvement in this research area. This paper serves to highlight some of the past developments of polymer nanocomposites and to inspire some potential fields that can be explored in high voltage electrical insulation perspective. Effect of the electrical discharges that causes the surface tracking and partial discharge phenomena on the polymer nanocomposites are the main subjects to be discussed in this pape

Electrical insulating characteristics of polymer nanocomposites for high voltage applications

Polymer nanocomposites have attracted wide interests in electrical insulating society due to its potential properties enhancement. In the present work, high density polyethylene (HDPE) nanocomposites containing 2 wt%, 5 wt% and 8 wt% of nanosized organically modified montmorillonite clay (nanoclay) were investigated, with unfilled HDPE served as reference material. The nanocomposites were prepared by using Brabender Plasticorder twin screw extruder. Scanning Electron Microscope (SEM) characterization was performed to determine the dispersion state of nanoclay in HDPE. Electrical insulating properties, mainly the surface tracking and internal discharge characteristics were investigated based on BS EN 60587: 2007 and CIGRE Method II test standards respectively. It was found that nanoclay negatively affected the surface tracking property of HDPE, in which higher amount of nanoclay causes more severe tracking progression. A degradation mechanism leading to the adverse effect of nanoclay towards surface tracking was proposed. In addition, contact angle measurement was performed to determine the hydrophobicity of the test samples. Results indicate that HDPE nanocomposites were less hydrophobic than unfilled HDPE. For internal discharge test, unfilled HDPE shows the highest resistance towards internal discharge. Interestingly, among nanocomposites, higher loading of nanoclay improved the internal discharge performance of the insulating material. Meanwhile, thermal characterization through Differential Scanning Calorimeter (DSC) shows that there is no significant difference observed for melting and cooling endotherms of HDPE nanocomposites and unfilled HDPE